In the past, as a method for recovering rare metals such as gallium, indium etc., from GaAs, GaAlAs, InGaAs etc., which are III-V group compound semiconductors, for example, an oxidation combustion method, a vacuum thermal recycling method are known.
An oxidation combustion method is for separating solid-state gallium oxide and gasiform arsine oxide by the following reaction:4GaAs (Solid)+6O2 (Gas)=2Ga2O3 (Solid)+As4O6 (Gas)
As a vacuum thermal recycling method, for example, as a method for recovering gallium and indium that gallium and indium are recovered at low cost from a compound semiconductor crystal scrap which gallium, indium and arsenic are a main component as mentioned in the Patent literature 1, a method for recovering gallium and indium after the semiconductor crystal scrap is heated under reduced pressure and then arsenic being sublimed, is known.
Further, the separation and refinement process using an ion-exchange resin can be carried out in the case that gallium and indium etc. are recovered from powdery waste metal, grinding waste liquid, and sludge which are generated in the manufacture or process of the III-V group compound semiconductors.
Patent literature 1: JP-A-2002-256355